Asahi Shimbun, June 11, 2013: The workers have yet to gain a grasp of the locations and condition of the fuel debris. They have yet to develop extraction equipment and determine removal methods.

Mainichi, June 11, 2013: Uncertainty over the location of melted fuel inside the crisis-hit Fukushima No. 1 Nuclear Power Plant continues to cast a shadow over plans to remove the fuel at an early date [...] Reactor Nos. 1-3 at the plant contained a total of 1,496 rods of nuclear fuel in their cores. [...] Each fuel rod weighs about 300 kilograms, and a high level of technical expertise would be required when undertaking a remote control operation to cut up and retrieve clumps of scattered radioactive materials weighing a combined 450 tons or thereabouts. [...] the cores of reactors at the Fukushima plant have holes, and the task at hand is finding which parts have been damaged [...] In a news conference on June 10, a representative of the Ministry of Economy, Trade and Industry’s Agency for Natural Resources and Energy said that bringing forward the plans would be dependent on developing technology, and suggested that the plans might even end up being delayed. [...]

1496 rods in each core.
Each rod weighs approx 300k
Thats 448800k
Or
204000lbs in each core
The article states 450 tons of fuel debris is scattered everywhere.
Each core contained 204000lbs or
102 tons of fuel rods approx per core
Where is the 450 ton # coming from.?

That 450 tons of fuel that was loaded in to the reactors and does not include the inventory in SFP.
How can you delay something that you do not comprehend, there is no time table and never will be, every step will be a step into the unknown with new technics needing to be established before proceeding and we all know that tepco is not up to the task to put it politely.
Even if we had full cooperation from all governments in the world, the speech from the UN would go something like this by the end of this century we will completely decommission Fukushima and it will take 75 % of gross national profit of all nations to accomplish, never to be fully decommissioned just mitigated.
Going to Mars is a walk in the park.
Time to re read Aurther C Clakes books once again, he was a visionary and much can be deducted.

Rats! The numbers don't line up correctly. Please follow the link to see the table. Anyway…

At 500 degrees C, Zircalloy mixes with steam to produce hydrogen.
Nuclear fuel (UO2) melted at 2865 degrees C.
The temperature of molten fuel may have reached 5000 degrees C.
The weight of fuel in Reactors1,2,&3 was 219 tons.
But the weight of the molten fuel on the bottom floor of Containments1,2,&3 included the mass of control rods, and lots of stainless steel, and the total weight of Corium1,2,&3 could easily have been 450 tons. By the time the corium exited Buildings1,2,&3, many tons of concrete and steel may have been added to the mass of the corium.

For the umpteenth time now, THEY HAVEN'T A CLUE WHERE THE CORIUM EVEN IS. 450 TONS of fuel so hot that even robots can't get near it; and even if they could, no technology to slice and dice the humongous pile of devil-dung.

Now they say that since THEY HAVEN'T A CLUE, and any plans will be "dependent on developing technology," that plans "might even end up being delayed"? You think? Like for a day, for a century, for forever??

What is also maddening (well, it all is) is that they keep talking about it like it was just an ENGINEERING problem. They never look at the REAL HUMAN AND ECOLOGICAL CONSEQUENCES of what they've done. But then again, the world does not either — any international bodies (like the IAEA) are so compromised, that they just rubber-stamp INSANITY.

EXACTLY… Thank you!!! It's as-if there is all-the-time-in-the-world to solve this "mystifying" technical problem, meanwhile the thousands of human casualties (among other affected species and ecosystems) are already piling up in the background (and they KNOW it). The "evil" of mis-handled nuclear power is bad-enough (but forgivable because humans make mistakes)…. But what is unforgivable is the "official" response. The propaganda, the lies, the denial… That's the problem, that's true "evil" (denying "murder," accidental or otherwise. It's just wrong). At least they could "get real" about what's happening & what's already happened and attempt to apologize for the lives & families that have-been and will-be DESTROYED as a result of their little "mystifying technical problem."

The link to the Manaichi write-up is unbelievable: "A draft announced by the government and Tokyo Electric Power Co. (TEPCO) on June 10 outlines plans to start removing the melted fuel about 18 months earlier than originally forecast."

"18 months earlier" than WHAT? 18 months earlier than centuries from now when they finally LOCATE the corium and "develop technology" to remove the 450-ton clump of devil-dung? 18 months earlier than the end of the world? 18 months earlier than their great-grandchildren are born deformed?

Note they blame the WORKERS for not having the technology, for the delay, for the problems. TEPCO-YOU are the worker. Guess by using the low class word 'worker' it takes the upper crust TEPCO off the hook?

That jumped out at me, also. Like those folks they keep dragging up there with no clue, and Tepco says it like those drones would have any knowledge of how to porceed, except at the end of a shovel. Sick.

If one tries to put a price tag on cleanup that is projected for a hundred years, how do we value the unborn, deformed, exposure caualties, life style changes, loss of productivity, and human disabilities? The value goes up over time. Especially since new power sources will need to come online. This will challenge humanity and civilization to a height never seen before.

My prediction is that Corium1,2,&3 are by now well below plant level, either under the reactors, or have followed the layers of mudrock into the seabed under the Pacific Ocean. Either way, Corium1,2,&3 are probably going to be impossible for humanity to do much about. Perhaps in 20 or 30 years, they will be talking about drilling wells around the corium to freeze it in place with liquid nitrogen. Corium lava tubes were left behind, filled with solidified molten mudrock, along with fuel debris. Disturbing the corium lava tubes, in an attempt to mitigate releases of radioactivity from them, or releases of radioactivity from the corium below through them, just has to be a very bad idea. In the end, TEP.gov will probably simply let Corium1,2,&3 go their way, fill Containments1,2,&3 with grout, and declare Diiachi Decommissioned.

The original estimations for the aggregate release were in exabecquerels (10*18), not petabecquerels (10*15). They keep looking only at cesium in the "adjusted" values, because it makes the total release look smaller than Chernobyl, instead of larger, as it was.

My 2 cents…
Assuming that the corium is no longer a liquid, (They say it is stable) I'm sure one could deduce this by measuring the temp of exiting water and water going in. Tunnel underneath it and place a new containment below it built to deal with it remotely as it melts down. Rate of melt down controlled by water flow. Is that too simple?

Suppose the 3 underground coriums pose a threat, that must be mitigated.
Suppose they actually locate the coriums, via ground penetrating radar, or some such.
Suppose the coriums are far underground.
Can you see Japan building a mine, surrounding each corium with a box of borated concrete?
Yes. I guess I could see that happening.
But only after the 40 year Decommissioning.
After they are forced to admit that the Corium is no longer inside the containment vessels.
And after the bulk of the damage to the Earth has been done. Sure.

your suggestion was submitted by me within the first days of 311. Unfortunately, word now has it they delayed far too long and inadvertently allowed the coreums to migrate to inaccessible regions within the geologic strata…

It was migrating the first day of the explosions and because it was porous sedimentary rock and landfill and explosions of nuclear material and the island itself had subsided 1 to 3 feet in the east, the corium has been flooding out and unrecoverable since day one.

Is it possible to save the corium from the ground water anywhere in the world when a nuclear plant melts down?

And with the melting of the Arctic ice cap, will any NPP on the ocean or on rivers leading into the ocean, be saved from a meltdown? Water and electricity don't mix, especially ocean water. And NPPs and nuclear reactors can't exist without electricity. And the Arctic ice cap melt is just symptomatic that the geomagnetic shield protecting the earth from the sun's radiation and CMEs (coronal mass ejections) has been breached. How soon will the transformers necessary for the NPPs be zapped out? How soon will incompetence cause the next meltdown in the US? We've already had three and have numerous nuclear waste dump sites. Isn't that enough to declare NPPs and nuclear reactors against the law?

Well, all it would take is a bad solar flare to knock out an electrical grid. Or if a natural disaster both wipes out a local grid and makes the plants inaccessible t outside help. It's Russian roulette, to put it charitably.

Yes and we won't spent the money to upgrade our infrastructure to deal with such a nasty CME but yet we have money to build two new AP1000 nuke plants in Georgia. Who woulda thunk it. I t's so frustrating.

The international nuclear scientists ran fairly large test corium melts (in Russia a few years ago) and they know how fast red hot corium can burn through steel and concrete.

The mudstone is probably not much more resistent than concrete. Despite their denials I suspect they know how deep the main nuclear lava masses have descended. Perhaps half a mile or deeper. It is a situation they would prefer to ignore and hope it finally cools on its own. Eventually it will, but how long is the trillion dollar question. Any water contacting it will stir it up or leach away radioisotopes.

How a large corium would interact if it reached methane layers is another consideration. Certainly the explosion potential is probably a non-issue because of inadequate oxygen levels, but what if the corium vent hole provides a steam outlet for methane clathrate to bubble in vast volumes to the surface accompanied by radiation fallout?

56 million years ago intense warming killed off most carbon forms on earth. It could happen again.

Another "They said WHAT??": The link to the Asahi Shimbun article above. It says that they plan on starting to remove "the fuel debris" in 2020, "18 months ahead of schedule."
("Debris" being another quaint term like "leak.")

WHAT "schedule"? Why don't they just say that they had planned on doing it in 2040, which means that it would be "20 years ahead of schedule"? Or if their (non-existent) plan had been for 2060, they could claim that they were doing it "40 years ahead of schedule"?

They don't even know where the so-called "debris" is, and it is 450 TONS [that they admit to] OUT OF CONTAINMENT. (And in no way in separate succinct rods. Not possible.) They have NO TECHNOLOGY, NO PLAN, to even get so far as to LOCATE it.

So this might just look like a bad circus of clinically-insane people trying to act normal. But the world does not even COVER it? And no one is willing/able to INTERVENE? If the Japanese want to commit suicide on behalf of their own population, tragic enough. But this will migrate HERE. It's RADIATION. There is a global atmosphere, there is a continuous ocean — the ongoing mediums of transmission. It's coming HERE. I shudder to think of what public realization might look like. The NON-response thus far has been scary.

"The best thing that could happen, after all the bad things that did, was for the corium to bury itself in the earth."
SwimsWithGators words of wisdom.
The corium has buried itself in the earth.
Fuku has decommissioned itself.
No new technologies will be necessary.
No new robots will be needed, after all.
TEPCO can now Issue a new Revised Roadmap:
Fill all the cracks with grout.
Fill the Torus and Torus Basements with grout.
Fill the SFPs with grout.
Fill the Containments and Reactors with grout.
Put all spent fuel into dry cask storage.
Filter all the water, and dump it into the ocean.
Spread a 10' layer of concrete on the Harbor bottom.
Build a concrete river to funnel groundwater to the sea.
Spread a 10' layer of reinforced concrete on the ground between the buildings.
Paint parking lot lines on the concrete.
Install brass placks to tell the story of each ruined reactor.
Print up an informative brochure for guests to pick up at the front gate on the way in.
Call it Fukushima Atomic Park.
Lay out an interprative walk.
Put in the Mutation Gardens.
Build the Support By Eating Restaurant, featuring a daily special of Pacific Blue Fin Tuna.
Offer exclusively 2011 vintage California wines.
A good time? You betcha!

Those coriums will haunt us on decades, Japan situation is worse because of groundwater pollution, it will go straight to food chain and future will tell the rest of story.

3# with MOX went sky high on huge blast, and there was enough plutonium for all of us, so bodycount after 10-20 years could be devastating.

This was a accident which could not happen, but it did. Sadly human doesn't have a decent tools for fixing this error. Every nuclear reactor and weapon must be destroyed asap, time to learn how to live peacefully and respect this globe, nature, really important things.

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